An insulation film is used to isolate various electronic devices or components to avoid malfunction caused by shortcircuiting, breakdown or the like between the electronic devices or components, or electronic elements in the electronic devices or components, and reduce the risk of catching fire of the electronic devices or components so as to guarantee normal operation of various electronic elements. For example, the insulation film is placed between a printed circuit board (PCB) containing various circuits and a metallic housing such as an aluminum or copper housing for preventing EMI (electromagnetic interference) to prevent problems such as shortcircuiting caused by contact between the various elements on the PCB and the metallic housing. In order to use the insulation film, the insulation film is required to have properties such as flame retardance, resistance against long-term high temperature, resistance against high pressure, inability to absorb water and good foldability. Furthermore, specific indices for the requirements for these properties of the insulation film vary with different requirements for insulation.
To meet the requirements for the properties of the insulation film, conventionally PP, PC and PET having halogenated flame retardants are used to manufacture the insulation film. However, the halogenated flame retardants are harmful for the environment. In order to eliminate the influence on the environment, attempts are made to reduce the amount of halogenated flame retardants used in PP, PC and PET or use PP, PC and PET having halogen-free flame retardants to manufacture the insulation film.
Since the raw material of PP is more inexpensive and exhibits a better folding endurance, insulation films made of PP are used more widely. However, because halogen-free flame retardants applicable to PP are hygroscopic, PP films containing halogen-free retardants are hygroscopic and as a result of which, PP films containing halogen-free retardants have a poor insulating property.
Therefore, it is desired to produce a PP insulting film containing halogenated flame retardants or halogen-free flame retardants which is produced at a lower cost, exhibits a better quality.